Apparatus for casting structural units for building construction

ABSTRACT

AN APPARATUS FOR CASTING A PLURALITY OF STRUCTURAL UNITS SUCH AS WALL PANELS OF PREDETERMINED CROSS-SECTIONAL SHAPE COMPRISING, A PAIR OF SPACED TRACKS, A DIE MEMBER CONFORMING TO SAID PREDETERMINED CROSS-SECTIONAL SHAPE ALONG ITS BOTTOM SURFACE, MEANS MOUNTING THE DIE MEMBER FOR MOVEMENT ALONG THE TRACKS, MEANS CONVEYING THE DIE ALONG THE TRACKS, AND MEANS AT THE FORWARD END OF THE DIE FOR EXTRUDING CONCRETE THERETHROUGH AND BENEATH THE MOVING DIE MEMBER UNDER PRESSURE. THE TOP SURFACE OF EACH PREVIOUSLY CAST UNIT SERVES AS A MOLD FOR THE BOTTOM SURFACE OF A SUBSEQUENTLY CAST UNIT.

Jan. 12, 1971 R. J. HORTON 3,553,797

I APPARATUS FOR CASTING STRUCTURAL UNITS FOR I BUILDING CONSTRUCTIONFiled Feb. 14, 1968 2 Sheets-$heet 1 INVENTOR ROBERT JACKSON HORTONATTORNEYS Jan. 12, 1971 R. HORTON 3,553,797

APPARATUS FOR C ING STRUCTURAL UNITS FOR BUILDING CONSTRUCTION FiledFeb. 14, 1968 2 Sheets-Sheet 2 FIGS P1 7 INVENT OR ROBERT JACKSON HORTONATTORNEYS United States Patent APPARATUS FOR CASTING STRUCTURAL UNITSFOR BUILDING CONSTRUCTION Robert J. Horton, 3192 Palomares Ave.,Lafayette, Calif. 94549 Filed Feb. 14, 1968, Ser. No. 705,339 Int. Cl.B28b 15/00 US. Cl. 25-2 2 Claims ABSTRACT OF THE DISCLOSURE An apparatusfor casting a plurality of structural units such as wall panels ofpredetermined crosssectional shape comprising, a pair of spaced tracks,a die member conforming to said predetermined cross-sectional shapealong its bottom surface, means mounting the die member for movementalong the tracks, means conveying the die along the tracks, and means atthe forward end of the die for extruding concrete therethrough andbeneath the moving die member under pressure. The top surface of eachpreviously cast unit serves as a mold for the bottom surface of asubsequently cast unit.

The present invention relates to an apparatus for casting concretestructural units useful in building construction.

Precast concrete structural units have been used in walls, floors, roofsand lateral declgingin building construction. Frequently, the unitscontain re-inforcing bars and sometimes these are prestressed. One ofthe difficulties with such building units has been their limited size,since such structural units are normally produced at a plant and thenare transported to the construction site. Though the structural unitsmay be produced in any desired size at the plant, as a practical matter,transportation consid erations make the manufacture of larger structuralunits impractical. State highway laws prevent the transporting by truckof structural units of a length and width above certain limits. Evenwhen transported by rail, freight hauling equipment frequently limitsthe size of structural units which may be transported. It therefore isimpossible in certain construction projects to use prefabricatedstructural units because of their limited size.

Also, such prefabricated units frequently, because of their shape,occupy a considerable amount of space while being transported, thusadding to the cost of transportation of such units.

An object of the present invention is the provision of an apparatus forproducing structural units of unlimited size which can be produced onthe construction site thus avoiding the size restrictions placed onstructural units which are normally transported along the publichighways or by rail.

Another object of the present invention is the production of structuralunits at a lower cost by eliminating the need for transportingprefabricated structural units and requiring only the transportation ofraw materials to the construction site at a considerably cheaper rate.

With these and other objects in view, the invention comprises anapparatus for carrying out these objects as will be hereinafter morefully described and illustrated in the accompanying drawings whichdisclose the preferred embodiments of the invention. It will beunderstood that though the apparatus is demonstrated as being useful forcasting concrete, the apparatus is equally useful for easting otherplastic materials used as gypsum.

In the accompanying drawings:

FIG. 1 is a plan view of the apparatus of the present invention;

3,553,797 Patented Jan. 12, 1971 FIG. 2 is a side view partially cutaway showing the apparatus of FIG. 1 in operation;

FIG. 3 is a schematic diagram showing the mechanical system fortransmitting power to drive the apparatus of FIG. 1;

FIG. 4 is a detailed view of the stacking bar located in the hopper ofthe apparatus;

FIG. 5 is a sectional view taken along the line V-V of FIG. 1;

FIG. 6 shows in greater detail the hold-down arrangement of FIG. 5;

FIG. 7 shows in cross-section the separation of continuously laidadjacent panels; and

FIG. 8 shows various examples of cross-sectional configurations ofpanels which may be produced by the process and apparatus of the presentinvention.

Similar reference characters indicate corresponding parts throughout theseveral views in the drawings.

Referring to the drawings in detail, and particularly FIGS. 1 and 2, theapparatus consists primarily of a power unit 1 to the underside of whichis adjustably secured a die 2. Hydraulic ram-s 23 extend between thepower unit and die to permit adjustment of the level of the die as willbe explained later. At the front of the die and extending upwardlyadjacent the front of the power unit is a hopper 3 for receiving andretaining a reservoir of wet concrete. The power unit 1 includes a setof four wheels 4 designed for use on the rails 15. All of the wheels arepower driven by conventional means which may include a gasoline engineor an electric motor 5 which through a chain drive 24 drives shaft 6 andaxles 7 transmitting power to the wheels to move the apparatus along therails 15.

The die 2 has a shape determined by a desired shape of the caststructural unit. A generally trough-like die is shown in use with theapparatus though different structural shapes will require substitutionof differently shaped dies which may be easily substituted on thehydraulic rams 23 at the bottom of the power unit.

A supply of concrete mix 8 is. maintained in the hopper 3 by anyconventional means, an example of which is shown in FIG. '1 wherein thefeed hopper 9, conveyor 10 and chute 11 are secured to the side of thepower unit. The conveyor is powered by a separate motor 12, the speed ofwhich may be regulated to maintain the proper level of concrete in thehopper 3'. The feed hopper 9 may be filled directly from a truckcarrying ready-mix concrete which may be driven alongside the feedhopper.

Adjacent the bottom end of the hopper 3 is a stacking bar 13 which isshown in detail in FIG. 4. The stacking bar should conform to thegeneral shape of the die in order that it may be located adjacent to theleading edge of the die. This requires that the stacking bar be replacedwhenever the die is changed so that the stacking. bar will conform tothe die. The stacking bar is reciprocally driven at a generally lowvelocity by motor 14 which is sealed and located at the center of thehopper. An appropriate rate of oscillation for the stacking bar is about900 oscillations per minute, though this will vary depending on the rateof travel of the apparatus and'the viscosity and type of concrete mixbeing laid.

Optionally, finishing tools 25 may be secured to the rear end of the dieand may be driven by a suitable power take-off arrangement from thepower unit 1. Finishing tools designed to trim off excess concrete atthe edges to develop the desired texture on the surface of the concretepanel may be used. An example of an appropriate finishing tool is arotating brush which creates a fine grain finish on the concretesurface.

The power unit 1 and its wheels 4- are supported on a set of parallelrails 15. The rails are preferably angular as shown in FIG. 6.Initially, the rails are mounted on stationary supports (not shown) butafter one or two superimposed structural units or panels have been laid,the rails are secured by bolts 16 to both sides of one or morepreviously laid structural units. With the laying of one or twoadditional structural units, it becomes each time necessary to raise therails a corresponding amount and to bolt them again in the raisedposition. The rails serve not only to support the power unit and die,but also serve as the side surfaces for retaining and shaping a newlypoured structural unit. The rails may be of any desired length dependingupon the length of the structural units being poured, and/ or the numberof individual structural units which are poured consecutively in end toend relationship at the same level. Thus, the rails may convenientlyrange between 100 feet and one to two thousand feet.

The rails serve a further function in holding down the power unit anddie in order that substantial pressure may be applied to the freshlypoured concrete during the shaping and finishig process. Adjacent to andparallel with the front and rear axles 7 of the power unit, arehold-down yo-kes 17. Attached to the end of each yoke and extendingdownwardly is a hold-down rod 18. The end of which is threaded adjacentthe yoke in order that a bolt 19 may be secured thereto. Secured to thelower end of each hold-down rod 18 is a hold-down roller which isdesigned to roll along the bottom edge of rail 15 as the power unitmoves. This necessitates that the lower portion of the rail be angled inorder that the hold-down rollers are clear of any obstruction. Bytightening bolt 19, the Wheels 4 are pressed against the top surface ofrail 15 and are prevented from being dislocated irrespective of theamount of pressure applied by the die to the surface of the freshlypoured concrete. Up to 20,000 pounds per square inch of pressure may beapplied to the concrete with the arrangement.

The method for producing the structural units and the operation of theabove apparatus will now be described. The above-described castingapparatus is transported to the construction site. Appropriately spacedstakes are driven into the ground in two parallel rows and the rails 15are attached thereto such that the surfaces of the rails opposite eachother are appropriately aligned a predetermined distance apart equal tothe width of the structural unit to be produced. A shallow trench isthen excavated between the rails and the power unit 1 is mounted on therails and secured thereto by the hold-down arrangement shown in FIG. 6.The die 2 of predetermined configuration is secured to the underside ofthe power unit after which the hydraulic rams 23 are adjusted such thatthe die surface is spaced only a small distance above the bottom of thetrench. Operation of conveyor 10 is begun and concrete mix is pouredinto feed hopper 9 which is thereby conveyed through chute 11 into thehopper 3. Motor 14 is started causing stacking bar 13 to oscillate and,simultaneously, the casting machine begins its movement forward alongthe rails whereby a thin layer of concrete is extruded into the trenchfrom hopper 3 to line the trench. The upper surface of the thin concretelining due to action of die 2 conforms to the shape of the desiredstructural unit to be produced. Once the initial lining has been laidand has been permitted to set, production of the individual structuralunits. may be initiated.

The power unit is returned to the starting end of the lined trough. Arelease coating is applied to the surface of the "concrete lining toprevent adhesion between the lining and the structural units.Reinforcing rods 21 if desired in the structural units are laid inappropriate positions raised from the surface of the trough lining. Inthe event that more than one structural unit is to be produced, plywoodseparation panels 22 are placed transversely in predetermined spacedrelationship in the trough. The height of the separation panel isslightly less than the desired thickness of the structural units so thatthe concrete may be poured continuously, but the set concrete may easilybe broken to form the individual structural units or panels.

Production of the first layer of structural units is then initiated byrepeating essentially the same procedure as was carried out in layingthe trough lining. The die elevation is adjusted by rams 23 such thatthe space between the die surface and the surface of the trough liningis equivalent to the predetermined thickness of the panel. As the powerunit moves forward, a 3 to 5 foot head of concrete mix 8 is maintainedin the hopper 3. Concrete mix may be continually poured into feed hopper9 from a truck which is slowly driven parallel and adjacent to thecourse followed by the power unit.

The stacking bar moving at about 900 oscillations per minute serves tocompress the extruded concrete mix below the die as it is moving forwardat the rate of between 2 and 10 feet per minute. With a die eight feetin length, the freshly poured concrete is retained under the die 2 forfrom three-quarters to four minutes. The stacking bar compresses theconcrete with suflicien': force that the die will maintain the pressureon the freshly-extruded concrete at up to 20,000 pounds per square inch.Because of the pressure being applied by the oscillating stacking bar,some of the concrete will be forced forward in advance of the hopper 3.As the die moves forward, the optional finishing tools attached to therear end of the die serve to give the top surface of the freshly laidconcrete the desired texture.

Upon reaching the end of the rails 15 the die 2 is raised by thehydraulic rams 23 and the power unit is returned to the oppositestarting end of the rails. Before the next layer of structural units maybe poured, sufficient time must elapse for the previous layer to set.However, it will be appreciated that if the tracks are of sufficientlength, the time required for the power unit to complete a single runfrom one end to the other will be nearly sufficient for the initial endof the layer to have set so that little time will be lost while theapparatus remains idle between runs.

Before each successive layer of structural units may be poured, thepreparatory steps including the placing of reinforcing rods 21 and theseparation panels 22 as well as the coating of the surface of thepreviously laid concrete with a releasing agent to prevent adherencebetween adjacent layers must be taken. In addition, the track 15 mayhave to be raised and bolted to a previously laid layer or layers ofconcrete.

The preceding steps involved in laying each layer of concrete to form aseries of structural units is repeated resulting in the layers beingstacked one upon the other. Up to 25 layers may be stacked conveniently.

As indicated earlier, the panels may be of most any shape. But, in anyevent, they must be of appropriate shape and thickness such that theymay be stacked one upon the other, the immediate prior layer serving asthe mold for the lower surface of the subsequent layer. Examples ofappropriate configurations for the panel are shown in FIG. 8.

Upon completion of the casting operation, the desired number of panelshaving been cast, the apparatus including tracks is removed leaving onlythe stack. Conventional lifting equipment, such as cranes, serve to liftconsecutively each panel from the top of the stack and without furtherhandling, it may be placed at the appropriate position for the buildingunder construction. Where multiple panels have been poured end to end,the free end of the panel is first lifted from the stack such that theopposite end, which is partially separated from the adjacent panel bythe upstanding plywood separator 22 will break away from the adjacentpanel immediately above the plywood panel forming a clean break at apredetermined position.

It may readily be seen that by using the described process andapparatus, a plurality of structural units may be produced at thebuilding construction site economically. Once produced, there need beonly a single step in handling the product, that being the conveying ofthe individual panels from the stack to the appropriate location in thebuilding under construction. Transportation problems have beeneliminated, particularly where the desired structural units areextremely large. The apparatus itself is not complex and may be easilytransported from one construction site to another.

As many embodiments may be made of the inventive concept, and as manymodifications may be made in the embodiment shown, it is to beunderstood that the above description is to be interpreted as merelyillustrative and not in a limiting sense.

I claim:

1. Apparatus for casting a plurality of concrete structural units on theground in the field one on top of the other using a first-cast one ofsaid units as a base form for casting subsequent ones of said units instacked relationship, comprising: a pair of parallel tracks spaced at apredetermined distance equal to the intended width of each said unit,said tracks serving as side forms for said first-cast one of said unitsand for each of said subsequent ones of said units; a trough-like diemember having a predetermined contour on its underside surface whichserves to shape the top surface of each of said units as they are cutone on top of the other; a Wheeled vehic e capable of moving along thetop of each said pair of tracks; regulating means securing said diemember to the underside of said vehicle for regulating the elevation ofsaid die; means for conveying said wheeled vehicle forwardly along saidtracks; plastic extrusion means adjacent the forward end of said diemember for extruding plastic material therethrough and beneath saidforwardly moving die member under pressure, said plastic extruslon meanscomprising a hopper having an opening at the bottom thereof adjacentsaid die member leading edge; means for forcing the plastic materialthrough said opening, said forcing means comprising a stacking barmounted within the plastic material, said bar having the samepredetermined contour along its underside surface as that of said diemember predetermined contour and being secured to an inner wall of saidhopper so that said stacking bar undersurface is substantially invertical alignment with said die member underside surface; means foroscillating said stacking bar; hold-down means securing said wheeledvehicle to said tracks during movement therealong, said hold-down meanscomprising holddown rollers mounted on said wheeled vehicle for passagealong the undersides of said tracks, whereby pressure by said die memberthrough said regulating means may be applied to the top surface of theextruded material during formation of said subsequent ones of said unitseach of uniform and identical cross-section by reason of said die memberpredetermined contour.

2. The apparatus according to claim 1 wherein said stacking baroscillating means is capable of oscillating at at least 900 oscillationsper minute.

References Cited UNITED STATES PATENTS 1,505,613 8/1924 Weston 25-103X1,559,014 10/1925 Snyder 25-103X 2,427,044 9/ 1947 Burns 25-10'3UX2,607,100 8/1952 Urschel 25131SC 2,818,790 1/1958 Canfield et al.25--118WUX 2,877,530 3/1959 Winn 251M 3,108,518 10/1963 OConner25-118WUX 3,143,781 8/1964 Kalns 252X 3,177,552 4/1965 Roth et a1. 2532X3,217,375 11/1965 Kinnard 2541.1 3,292,227 12/1966 Olds 252 J. HOWARDFLINT, In, Primary Examiner US. Cl. X.R.

25--11 32, 103, 118, 131; 249-l3; 264layers dig.

